A good “poker face” can hide the quality of your cards. But your arms might still be giving away your hands. That’s the finding of a study to come out in the journal Psychological Science. [Michael L. Slepian et al., Quality of Professional Players’ Poker Hands is Perceived Accurately from Arm Motions, link to come]

Volunteers watched videos of the World Series of Poker. The videos were edited so the subjects saw one of three different views of the players: the poker players’ entire bodies from the table up, or just the players’ faces or just the players’ arms pushing chips into the pot. “When participants were watching chips being pushed into the center of the table by the players, it was only then could they accurately perceive how good a hand was better than chance. They couldn’t do it for the whole body and if anything they were worse from just watching the face.” Michael Slepian, a psychology doctoral student at Stanford University, and a co-author of the study.

No pros were among the video watchers. But there’s some evidence that, as might be expected, they’d be even better at catching arm cues. “In one of our studies, the more participants were familiar with poker—even though they were all novices—the better they did.”